Doblo T-Jet only crank if sit Doblo Tjet with CNG. Arrived a little out of timing, s

[alessioblaupunkt]

Doblo T-Jet only crank if sit

Doblo Tjet with CNG.
Arrived a little out of timing, so it turned over but never started.
After correcting sync on timing, the first attempt is a crank no start.
You have to leave the key on for half a minute then it will start and run well.
If you repeat crank, it will start immediately.
If you let it sit for 3 hours, again crank no start.
Again, turn the key and wait half a minute then it will start and run well.
With OEM diagnostic no fault stored.
Compression is fine on all four cylinder.
Spark plug are new.
Bought a new OEM ECU but problem is not solved.

With diagnostic temperature of air and water are ok.

Have disconnected the CNG circuit but problem is not related with CNG.

[mihac]

Check voltage supply on board, when cranking. (example:loss voltage in groundwire).

[DiegoStud]

I reckon lambda related-
How old is the fuel if it's been running CNG mostly i assume?
Do you have lambda readings while cranking?
I know you say its not CNG but are you sure? By disconnected CNG do you mean electrically or gas supply removed?
Leaking CNG valves will richen up the inlet manifold over time, when starting is attempted lambda sensor will correct and shut off fuel to prevent flooding. Give it 30 seconds for the lambda readings to drop and away you go.

[Meat-Head]

Both above posts are awesome and agree with

start with as its a fiat

1) try push starting
2) jumper cables from another car
3) jumper cable from battery - to engine block

[alessioblaupunkt]

@DiegoStud
Fuel is new. According to Fiat documentation, the 2008-2014 CNG model
ALWAYS start with petrol then it will switch to CNG.
I will check lambda readings while cranking.

CNG has been disconnected both electrical and gas supply.

@MH
Nice to test all of these, but if problem reappear every 3 hours
of non use, I need 9 hours to do those test.

Problem is customer want the van asap after spending a lot of money.

Such a bastard fault, isn't it?

[Meat-Head]

Reading again, sounds like immboliservl not release as voltage dropping
deffo connect jumper cables

[alessioblaupunkt]

SOLVED

Old petrol.

Fuel WAS NOT new.
On 18th October I phoned to customer and it was angry for bill, time, van running as before, etc.
The first thing I asked him was:
<<It was low on petrol, have you done petrol?>>
His answer:
<<Yes, I've done petrol>>
THAT'S FALSE:
the van returned with nealy empty tank and when we took out the 3 liters
inside, the van with new petrol started immediately, and three hours later,
and again the morning after.

Another (expensive) happy customer (FALSE and time waster).